1. The combination of agronomic practices could be an effective method for action to reduce the oidium pressure during the growing flax cycle. Lower pressure would provide a lower use of plant protection products. 2. The tested alternative plant protection products are not on the flax approved list. The efficiency of these products on disease development is required to put them on the flax approved list. 3. Keeping flax fields weed-free only using mechanical weeding or reducing the use of phytosanitary products with mechanical weeding. The first project lessons are about the importance of soil and weather conditions during the sowing operation. Unfavorable sowing conditions lead to poor control of emerged flax plants, thus to low yield results. Neither flax crops nor agronomic practices can  ompensate for the loss of emerged plants. The respect of favorable soil and weather conditions is the best method for action to obtain economic benefits. We also obtain good results with some biocontrol products against oidium that are as good, so far, as conventional products.